Method for preparing vanadium electrolyte by using aluminum oxide seed precipitation mother liquor crystallization vanadium slag

Abstract

The invention provides a method for preparing a vanadium electrolyte by using aluminum oxide seed precipitation mother liquor crystallization vanadium slag, which comprises the following steps: carrying out reduction acid leaching on Bayer process seed precipitation mother liquor crystallization vanadium slag, converting V (V) and As (V) into V (IV) and As (III), adding an arsenic removal precipitator for arsenic removal, and further hydrolyzing to obtain VO (OH) 2; vO (OH) 2 is converted into a pentavalent vanadate solution through oxidation alkaline leaching, impurity ions such as arsenic, phosphorus, aluminum and silicon are further removed through multiple times of crystallization, and high-purity vanadate is obtained; and finally, high-purity vanadate is converted into a V (IV) solution through reduction acid leaching, an arsenic removal precipitator is added again, deep arsenic removal is achieved, VO (OH) 2 is obtained through hydrolysis, and VOSO4 electrolyte is prepared through sulfuric acid dissolution.

Description

Technical Field

[0001] The invention relates to the field of preparation of vanadium electrolyte, in particular to a method for preparing vanadium electrolyte by utilizing alumina seed solution and crystallizing vanadium slag. Background Art

[0002] Bauxite is an important potential vanadium resource. The Bayer process is the most widely used method for extracting alumina from bauxite. Alumina is obtained from bauxite through the steps of dissolution-seed decomposition-high temperature roasting. During the dissolution process, the aluminum in the bauxite is converted into sodium aluminate and enters the mother liquor. At the same time, more than 30% of the vanadium in the bauxite and some impurities such as phosphorus, arsenic, and silicon will also dissolve into the mother liquor and continue to be enriched with the circulation of the mother liquor, which will harm the subsequent aluminum hydroxide seed decomposition process.

[0003] At present, the evaporation cooling crystallization method is widely used in industry to remove impurities such as vanadium, phosphorus, arsenic, and silicon from the Bayer process mother liquor. The crystals obtained by crystallization can be further processed to obtain V 2 O 5 The vanadium slag with a vanadium content of 10%-20% is called the crystallized vanadium slag of the seed liquor of Bayer process alumina. At present, the process of treating the vanadium slag in alumina plants is generally to dissolve it in water and then directly precipitate vanadium with ammonium salt to obtain crude ammonium metavanadate, and further roasting can obtain crude V containing higher content of impurities such as phosphorus, arsenic, silicon, aluminum, etc. 2 O 5 , the purity is low, and the cost of treating the high-salt ammonia nitrogen wastewater produced by ammonium salt precipitation of vanadium is very high, which further aggravates the cost pressure and environmental pollution problems of alumina plants.

[0004] The Chinese invention patent application with the publication number CN 116904772 A discloses a process for extracting vanadium from crystallized vanadium slag from the seed denominator liquid of the Bayer process alumina. The vanadium slag is first dissolved in sodium hydroxide, and lead sulfate is added to precipitate vanadium. The liquid after vanadium precipitation is cooled, crystallized, filtered and returned to the dissolution step. The vanadium-enriched slag is leached with sulfuric acid and a reducing agent to obtain a vanadium-enriched liquid. This method does not require ammonium salt precipitation of vanadium, which avoids the generation of ammonia nitrogen wastewater, but the lead-containing wastewater generated is still harmful to the environment, and the vanadium-enriched liquid generated still needs to be further processed by extraction and other processes. The Chinese invention patent application with the publication number CN 116397112 A discloses a method for separating and extracting vanadium from crystallized vanadium slag from the seed denominator liquid of the Bayer process. The vanadium slag is dissolved in sodium hydroxide and then barium salt is added to selectively precipitate vanadium. The liquid after vanadium precipitation is cooled, crystallized, filtered and returned to the dissolution step. The precipitated vanadium slag is leached with a leaching agent or converted to an acid solution and then leached with a leaching agent to obtain leached slag and vanadium-enriched liquid. The vanadium-enriched liquid is precipitated with ammonium salt to obtain a vanadium product. This method consumes less acid / alkali and has a high vanadium recovery rate, but the recovery of vanadium products still requires an ammonium salt precipitation process. At the same time, the above methods are all targeted at the deep removal of impurity elements in vanadium slag, and can only obtain crude vanadium products with high impurity content and low purity.

[0005] All-vanadium flow battery electrolyte is a high-value vanadium product, mainly composed of expensive high-purity V 2 O 5 As raw material preparation, high purity V 2 O 5 Usually 98% rough V 2 O 5 As raw material, after long-process purification and preparation, a large amount of highly polluted ammonia nitrogen wastewater will be discharged, which also leads to a high cost of vanadium electrolyte. If the vanadium slag crystallized from the Bayer process denominator liquor is used as raw material for the short-process and clean preparation of vanadium electrolyte, it can not only reduce the preparation cost of vanadium electrolyte, but also realize the high-value utilization of vanadium slag. However, vanadium electrolyte has high requirements for impurities, and vanadium slag is rich in various types of high-content impurity elements. Therefore, the deep purification and removal of various types of impurities in the process of preparing vanadium electrolyte from vanadium slag crystallized from the Bayer process denominator liquor is the key.

[0006] The Chinese invention patent application with publication number CN 116404220 A provides a method for preparing a high-concentration vanadium electrolyte by crystallization purification of vanadates-chemical reduction, using crude vanadium and other vanadium-containing materials as raw materials, obtaining high-purity vanadates by alkali dissolution-crystallization purification, and then preparing vanadium electrolyte by chemical reduction of high-purity vanadates. This method is a wet process throughout, and does not require reagents such as ammonium salts and impurity removers. However, the raw materials used in this method are industrial products such as crude vanadium and ammonium vanadate with high vanadium content and low impurity content, so it is not suitable for crystallization of vanadium slag from Bayer process denominator liquor with high impurity content.

[0007] In summary, the existing methods for extracting vanadium and preparing electrolyte cannot achieve the purification and removal of impurities from the crystallized vanadium slag of the Bayer process alumina seed liquor and the preparation of vanadium electrolyte. It is urgent to develop a method for purifying and removing impurities from the crystallized vanadium slag of the Bayer process seed liquor and preparing vanadium electrolyte. Summary of the invention

[0008] In order to solve the problems existing in the prior art, the present invention provides a method for preparing vanadium electrolyte by using vanadium slag crystallized from alumina seed liquor, aiming to realize the purification and impurity removal of vanadium slag crystallized from alumina seed liquor produced by the Bayer process and the preparation of vanadium electrolyte, so that the obtained vanadium electrolyte meets the requirements of GB / T 37204-2018 for first-class quadrivalent vanadium electrolyte, and at the same time reduces the production cost of vanadium electrolyte.

[0009] According to one aspect of the present invention, a method for preparing vanadium electrolyte by using alumina seed liquor and crystallizing vanadium slag is provided, wherein the alumina seed liquor is a Bayer process alumina seed liquor, and the method comprises the following steps:

[0010] 1) Dissolve the crystallized vanadium slag of the Bayer process alumina seed liquor in acid, adjust the solution pH to 0-5, add the first reducing agent according to 1.1-3 times the theoretical amount of the first reducing agent required for reducing V(V) and As(V) to V(IV) and As(III), react at 25-99° C. for 0.5-5 hours to obtain a V(IV) solution, adjust the pH value of the V(IV) solution to -1-5, add the arsenic removal precipitant in multiple times according to 3-9 times the theoretical amount of the arsenic removal precipitant required for removing As(III), and react at 25-99° C. for 0.5-2 hours to obtain an arsenic-removed V(IV) solution, adjust the pH value of the arsenic-removed V(IV) solution to 5-14, and filter to obtain VO(OH) 2 Solid; wherein the first reducing agent includes one or more of sodium sulfide, elemental sulfur, sulfur dioxide, sulfite, oxalic acid, oxalate, glucose, fructose, sucrose, and formic acid;

[0011] 2) VO(OH) obtained in step 1) 2 The solid is placed in an alkaline solution and the pH value is adjusted to 7-14, an oxidant is added according to 1.5-5 times the theoretical amount required for oxidation of V(IV) to V(V), and the reaction is carried out at 25-99°C for 0.5-2 h to obtain a pentavalent vanadate solution, and then the vanadate solution is cooled to 0-25°C at a rate of 0.1-5°C / min, and the solution is stirred at a rate of 20-200 r / min. The cooled solution is filtered to obtain vanadate crystals; and then the vanadate crystals replace VO(OH) 2 Repeat step 2) for more than one time using the solid as the raw material to obtain high-purity vanadate crystals with a purity greater than 99.9%;

[0012] 3) Dissolve the high-purity vanadate crystals obtained in step 2) in acid, and adjust the pH value to 0-5, add a second reducing agent according to 1.1-3 times the theoretical amount of the second reducing agent required for reducing V(V) and As(V) to V(IV) and As(III), react at 25-99° C. for 0.5-5 h, adjust the pH value of the solution to -1-5, add an arsenic removal precipitant in multiple times according to 3-9 times the theoretical amount of the arsenic removal precipitant required for removing As(III), and react at 25-99° C. for 0.5-2 h to obtain an arsenic removal solution, adjust the pH value of the arsenic removal solution to 5-14, and filter to obtain VO(OH) 2 , the VO(OH) 2 After acid washing and water washing, the VO(OH) 2 , preparing a vanadium electrolyte; wherein the second reducing agent includes one or more of sodium sulfide, elemental sulfur, sulfur dioxide, sulfite, oxalic acid, oxalate, glucose, fructose, sucrose, and formic acid.

[0013] As a preferred embodiment of the method for preparing vanadium electrolyte by using alumina seed liquor crystallized vanadium slag of the present invention, the Bayer process alumina seed liquor crystallized vanadium slag comprises V 2 O 5 10~20 wt%, Al 0.5~1 wt%, As 0.5~3 wt%, P 1~3 wt%, Si 0.1~1 wt%.

[0014] As a preferred embodiment of the method for preparing vanadium electrolyte by using alumina seed liquor crystallized vanadium slag, in step 1), the acid comprises dilute sulfuric acid with a concentration of 40-100 g / L, and the solid-to-liquid ratio of the alumina seed liquor crystallized vanadium slag to the dilute sulfuric acid is 1:1-1:10 g / mL.

[0015] As a preferred embodiment of the method of preparing vanadium electrolyte by crystallizing vanadium slag from alumina seed liquor, the pH value is adjusted as follows: when the pH value needs to be lowered, one or more acids including sulfuric acid and hydrochloric acid are added to the solution for adjustment; when the pH value needs to be increased, one or more bases including NaOH and KOH are added to the solution for adjustment.

[0016] As a preferred embodiment of the method for preparing vanadium electrolyte by using alumina seed liquor and crystallizing vanadium slag, the arsenic removal precipitant includes one or more of sodium sulfide, potassium sulfide, ammonium sulfide, hydrogen sulfide and thiourea. The theoretical amount of arsenic removal precipitant required for removing As(III) is specifically: As(III) reacts with the arsenic removal precipitant to generate As 2 S 3 The theoretical amount of arsenic removal precipitant required.

[0017] As a preferred embodiment of the method for preparing vanadium electrolyte by crystallizing vanadium slag from alumina seed liquor, the multiple times in step 1) is 3 to 5 times.

[0018] As a preferred embodiment of the method for preparing vanadium electrolyte by crystallizing vanadium slag from alumina seed liquor of the present invention, in step 2), the oxidant includes one or more of hydrogen peroxide, sodium peroxide, potassium peroxide, ammonium persulfate, sodium persulfate, and potassium persulfate.

[0019] As a preferred embodiment of the method for preparing vanadium electrolyte by crystallizing vanadium slag from alumina seed liquor of the present invention, in the step 2), the alkali solution comprises one or more of NaOH and KOH solutions with a concentration of 50-500 g / L.

[0020] As a preferred embodiment of the method for preparing vanadium electrolyte by crystallizing vanadium slag from alumina seed liquor, the multiple times in step 3) is 3 to 5 times.

[0021] As a preferred embodiment of the method for preparing vanadium electrolyte by crystallizing vanadium slag from alumina seed liquor of the present invention, in step 3), the reagent used for pickling is dilute sulfuric acid with a pH of 5 to 7, the number of washing times for pickling is 1 to 3 times, and the number of washing times for water washing is 2 to 3 times; the reagent used for acid dissolution is sulfuric acid with a concentration of 4 to 6 mol / L.

[0022] In the present invention, the Bayer process seed liquor crystallized vanadium slag is subjected to reduction acid leaching, V(V) and As(V) therein are converted into V(IV) and As(III), and an arsenic removal precipitant is added to remove arsenic, and then VO(OH) is further hydrolyzed. 2 ;VO(OH) 2 The vanadate is converted into a pentavalent vanadate solution by oxidative alkaline leaching, and then the impurity ions such as arsenic, phosphorus, aluminum, and silicon are further removed by multiple crystallizations to obtain high-purity vanadate. Finally, the high-purity vanadate is converted into a V(IV) solution by reducing acid leaching, and an arsenic removal precipitant is added again to achieve deep arsenic removal, and VO(OH) is obtained by hydrolysis. 2 VOSO was prepared by sulfuric acid dissolution 4 Electrolyte.

[0023] In the technical solution of the present invention, all contents are by mass unless otherwise specified, As(V) refers to pentavalent arsenic, As(III) refers to trivalent arsenic, V(V) refers to pentavalent vanadium, and V(IV) refers to tetravalent vanadium.

[0024] Compared with the prior art, this invention has the following beneficial effects:

[0025] 1. The present invention uses the crystallization vanadium slag of the Bayer process alumina seed liquor as raw material to produce vanadium electrolyte, realizing the resource utilization and high-value utilization of vanadium in bauxite, and the washing liquid obtained by acid washing and water washing can be used to dissolve high-purity vanadate crystals. According to calculations, compared with the traditional production process of preparing vanadium electrolyte from vanadium slag obtained from vanadium-titanium magnetite, the production cost of vanadium electrolyte can be reduced by more than 50%.

[0026] 2. The arsenic, aluminum, silicon and other impurities in the crystallized vanadium slag of the Bayer process seed denominator liquid are removed in depth by three stages of precipitation-crystallization-precipitation, with a high impurity removal rate. The obtained vanadium electrolyte has high purity and can meet the requirements of GB / T 37204-2018 for first-class 4-valent vanadium electrolyte. The impurity content of the vanadium electrolyte obtained based on the scheme of the present invention is As≤0.8 ppm, Al≤1.8 ppm, and Si≤1.2 ppm.

[0027] 3. The whole process of the present invention is a wet process, which does not require high-temperature calcination, has low energy consumption, low cost, is easy to operate, and does not produce difficult-to-treat wastes such as ammonia nitrogen wastewater and organic pollutants. The solution in the whole process can be recycled through purification, and the process is clean. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 Schematic diagram of the preparation method of the present invention

[0029] Figure 2 Actual picture of vanadium electrolyte obtained by the preparation method of the present invention DETAILED DESCRIPTION

[0030] The following will be described clearly and completely in conjunction with the technical solutions in the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] Example 1

[0032] A method for preparing vanadium electrolyte by using Bayer process aluminum oxide seed liquor crystallized vanadium slag, wherein the main components of the Bayer process aluminum oxide seed liquor crystallized vanadium slag include V 7.7%, Na 18.4%, As 1.4%, P1.3%, Al 0.6%, and Si 0.3%, and the method comprises the following steps:

[0033] 1) 200 g of Bayer process alumina seed mother liquor crystallized vanadium slag was dissolved in 80 g / L dilute sulfuric acid at a solid-liquid ratio of 1:3, sulfuric acid was used to adjust the pH value of the solution to 1, 27 g of oxalic acid was added, and the reaction was carried out at 60°C for 2 h to obtain a V(IV) solution, sulfuric acid was added to adjust the pH value of the V(IV) solution to 2, 27 g of sodium sulfide (9 g each time) was gradually added in 3 times, and the reaction was carried out at 60°C for 1 h to obtain an arsenic-free V(IV) solution, NaOH was added to adjust the pH value of the arsenic-free V(IV) solution to 7, and VO(OH) was obtained by filtration. 2 solid;

[0034] 2) VO(OH) obtained in step 1) 2 The solid was mixed with 10.2 g of hydrogen peroxide, dissolved in 300 ml of 100 g / L NaOH solution and adjusted to pH 9 using dilute sulfuric acid, reacted at 60 °C for 1 h to obtain a pentavalent sodium vanadate solution, then cooled to 20 °C at a rate of 1.4 °C / min, stirred at a rate of 200 r / min during the cooling process, and the cooled solution was filtered to obtain sodium vanadate crystals; then the sodium vanadate crystals were used to replace VO(OH) 2 The solid was used as a raw material and step 2) was repeated twice to obtain 55.2 g of high-purity sodium vanadate crystals with a purity of 99.93% and an As content of 0.06 wt%;

[0035] 3) The high-purity sodium vanadate crystals obtained in step 2) were dissolved in sulfuric acid, and the pH value was adjusted to 1, 30.24 g of sodium sulfite was added, and the reaction was carried out at 60° C. for 2 h, and NaOH was added to adjust the pH value of the solution to 2, and 0.3 g of sodium sulfide (0.1 g each time) was added in 3 times, and the reaction was carried out at 60° C. for 1 h to obtain an arsenic-free solution with an arsenic content of 3.4 ppm, and NaOH was added to adjust the pH value of the arsenic-free solution to 7, and VO(OH) was obtained by filtration. 2 , the VO(OH) 2 After being washed twice with dilute sulfuric acid at pH 6.5 and twice with water, 150 mL of 4.2 mol / L sulfuric acid was used to dissolve the washed VO(OH) 2 , and a 1.6 mol / L vanadyl sulfate electrolyte was prepared.

[0036] It was determined that the vanadyl sulfate electrolyte prepared in this embodiment had Na 42 ppm, As 0.2 ppm, Al 1 ppm, and Si 1.2 ppm, which met the requirements of GB / T 37204-2018 for first-grade quadrivalent vanadium electrolyte.

[0037] Example 2

[0038] A method for preparing vanadium electrolyte by using Bayer process alumina seed liquor crystallized vanadium slag, wherein the main components of the Bayer process alumina seed liquor crystallized vanadium slag include V 8.2%, Na 17.3%, As 1.2%, P 1.5%, Al 1%, and Si 0.4%, and the method comprises the following steps:

[0039] 1) 200 g of Bayer process alumina seed mother liquor crystallized vanadium slag was dissolved in 70 g / L dilute sulfuric acid at a liquid-solid ratio of 1:5, KOH was used to adjust the pH value of the solution to 3, 5.14 g of elemental sulfur was added, and the reaction was carried out at 40°C for 5 h to obtain a V(IV) solution, sulfuric acid was added to adjust the pH value of the V(IV) solution to 0, a total of 21.12 g of potassium sulfide (5.28 g each time) was gradually added in 4 times, and the reaction was carried out at 40°C for 1 h to obtain an arsenic-free V(IV) solution, NaOH was added to adjust the pH value of the arsenic-free V(IV) solution to 9, and VO(OH) was obtained by filtration. 2 solid;

[0040] 2) VO(OH) obtained in step 1) 2The solid was mixed with 52.8 g potassium peroxide, dissolved in 300 ml 150 g / L KOH solution and adjusted to pH 12 using KOH, reacted at 80 °C for 1 h to obtain a pentavalent potassium vanadate solution, then cooled to 10 °C at a rate of 2.5 °C / min, stirred at a rate of 100 r / min during the cooling process, and the cooled solution was filtered to obtain potassium vanadate crystals; then the potassium vanadate crystals replaced VO(OH) 2 The solid was used as a raw material and step 2) was repeated twice to obtain 59.4 g of high-purity potassium vanadate crystals with a purity of 99.91% and an As content of 0.08 wt%;

[0041] 3) The high-purity potassium vanadate crystals obtained in step 2) were dissolved in sulfuric acid, and the pH value was adjusted to 3. 17.28 g of oxalic acid was added, and the reaction was carried out at 40° C. for 5 h. Sulfuric acid was added to adjust the pH value of the solution to 0. 0.418 g of potassium sulfide (0.1054 g each time) was added in 4 portions, and the reaction was carried out at 40° C. for 1 h to obtain an arsenic-free solution with an arsenic content of 5.2 ppm. NaOH was added to adjust the pH value of the arsenic-free solution to 10, and VO(OH) was obtained by filtration. 2 , the VO(OH) 2 After being washed twice with dilute sulfuric acid at pH 6.5 and twice with water, 120 mL of 5 mol / L sulfuric acid was used to dissolve the washed VO(OH) 2 , and a 2 mol / L vanadyl sulfate electrolyte was prepared.

[0042] It was determined that the vanadyl sulfate electrolyte prepared in this embodiment contained 36 ppm Na, 0.5 ppm As, 1.8 ppm Al, and 1 ppm Si, which met the requirements of GB / T 37204-2018 for first-grade tetravalent vanadium electrolyte.

[0043] Example 3

[0044] A method for preparing vanadium electrolyte by using Bayer process alumina seed liquor crystallized vanadium slag, wherein the main components of the Bayer process alumina seed liquor crystallized vanadium slag include V 6.8%, Na 15.4%, As 1.9%, P 2%, Al 2%, and Si 1%, and the method comprises the following steps:

[0045] 1) 200 g of Bayer process alumina seed mother liquor crystallized vanadium slag was dissolved in 80 g / L dilute sulfuric acid at a liquid-solid ratio of 1:7, sulfuric acid was used to adjust the pH value of the solution to 0, 20.16 g of sodium sulfite was added, and the reaction was carried out at 25°C for 5 hours to obtain a V(IV) solution, sulfuric acid was added to adjust the pH value of the V(IV) solution to 0, a total of 52.65 g of sodium sulfide (10.53 g each time) was gradually added in 5 times, and the reaction was carried out at 25°C for 2 hours to obtain an arsenic-free V(IV) solution, NaOH was added to adjust the pH value of the arsenic-free V(IV) solution to 11, and VO(OH) was obtained by filtration. 2 solid;

[0046] 2) VO(OH) obtained in step 1) 2 The solid was mixed with 52.65 g of sodium peroxide, dissolved in 250 ml of 200 g / L NaOH solution and adjusted to pH 7 with sulfuric acid, reacted at 40 °C for 1 h to obtain a pentavalent sodium vanadate solution, then cooled to 2 °C at a rate of 0.5 °C / min, stirred at a rate of 100 r / min during the cooling process, and the cooled solution was filtered to obtain sodium vanadate crystals; then the sodium vanadate crystals were used to replace VO(OH) 2 The solid was used as a raw material and step 2) was repeated twice to obtain 40 g of high-purity sodium vanadate crystals with a purity of 99.95% and an As content of 0.04 wt%;

[0047] 3) The high-purity sodium vanadate crystals obtained in step 2) were dissolved in sulfuric acid, and the pH value was adjusted to 0. 9.72 g of formic acid was added, and the reaction was carried out at 25° C. for 5 h. Sulfuric acid was added to adjust the pH value of the solution to 0. 0.22 g of sodium sulfide (0.044 g each time) was added in 5 portions, and the reaction was carried out at 25° C. for 2 h to obtain an arsenic-free solution with an arsenic content of 6.4 ppm. NaOH was added to adjust the pH value of the arsenic-free solution to 14, and VO(OH) was obtained by filtration. 2 , the VO(OH) 2 After being washed twice with dilute sulfuric acid at pH 6.5 and twice with water, 120 mL of 5 mol / L sulfuric acid was used to dissolve the washed VO(OH) 2 , and a 1.7 mol / L vanadyl sulfate electrolyte was prepared.

[0048] It was determined that the vanadyl sulfate electrolyte prepared in this embodiment contained 23 ppm Na, 0.5 ppm As, 1.6 ppm Al, and 0.7 ppm Si, which met the requirements of GB / T 37204-2018 for first-class quadrivalent vanadium electrolyte.

[0049] Example 4

[0050] A method for preparing vanadium electrolyte by using Bayer process alumina seed liquor crystallized vanadium slag, wherein the main components of the Bayer process alumina seed liquor crystallized vanadium slag include V 10.5%, Na 15.5%, As 1%, P 2.4%, Al 1.2%, and Si 0.4%, and the method comprises the following steps:

[0051] 1) 500 g of Bayer process alumina seed liquor crystallized vanadium slag was dissolved in 40 g / L dilute sulfuric acid at a solid-liquid ratio of 1:9, sulfuric acid was used to adjust the pH value of the solution to 0, 97.6 g of potassium sulfite was added, and the reaction was carried out at 30 ° C for 5 h to obtain a V(IV) solution, sulfuric acid was added to adjust the pH of the V(IV) solution to -1, a total of 20.4 g of ammonium sulfide (5.1 g each time) was gradually added in 4 times, and the reaction was carried out at 30 ° C for 2 h to obtain an arsenic-free V(IV) solution, NaOH was added to adjust the pH value of the arsenic-free V(IV) solution to 13, and VO(OH) was obtained by filtration. 2 solid;

[0052] 2) VO(OH) obtained in step 1) 2 The solid was mixed with 70 g of hydrogen peroxide, dissolved in 1 L of 330 g / l KOH solution and adjusted to pH 8 using sulfuric acid, reacted at 30 °C for 2 h to obtain a pentavalent potassium vanadate solution, then cooled to 2 °C at a rate of 0.1 °C / min, stirred at a rate of 200 r / min during the cooling process, and the cooled solution was filtered to obtain potassium vanadate crystals; then the potassium vanadate crystals replaced VO(OH) 2 The solid was used as a raw material and step 2) was repeated three times to obtain 200 g of high-purity potassium vanadate crystals with a purity of 99.91% and an As content of 0.09 wt%;

[0053] 3) The high-purity potassium vanadate crystals obtained in step 2) were dissolved in sulfuric acid, and the pH value was adjusted to -1, 61.8 g of potassium oxalate was added, and the reaction was carried out at 30 ° C for 5 h, sulfuric acid was added to adjust the pH value of the solution to -1, 0.75 g of ammonium sulfide was added three times (0.25 g each time), and the reaction was carried out at 30 ° C for 2 h to obtain an arsenic-free solution with an arsenic content of 3.2 ppm, KOH was added to adjust the pH value of the arsenic-free solution to 13, and VO(OH) was obtained by filtration. 2 , the VO(OH) 2 After being washed once with dilute sulfuric acid at pH 6.5 and three times with water, the washed VO(OH) was dissolved in 270 mL of 6 mol / L sulfuric acid. 2 , and a 3 mol / L vanadyl sulfate electrolyte was prepared.

[0054] It was determined that the vanadyl sulfate electrolyte prepared in this embodiment contained 46 ppm Na, 0.8 ppm As, 1.2 ppm Al, and 0.8 ppm Si, which met the requirements of GB / T 37204-2018 for first-grade tetravalent vanadium electrolyte.

[0055] Example 5

[0056] A method for preparing vanadium electrolyte by using Bayer process alumina seed liquor crystallized vanadium slag, wherein the main components of the Bayer process alumina seed liquor crystallized vanadium slag include V 9.6%, Na 13.2%, As 1.2%, P 2%, Al 1.3%, and Si 0.5%, and the method comprises the following steps:

[0057] 1) 300 g of Bayer process alumina seed mother liquor crystallized vanadium slag was dissolved in 40 g / L dilute sulfuric acid at a solid-liquid ratio of 1:10, and the pH value of the solution was adjusted to 5 with NaOH. 82.3 g of sodium oxalate was reacted at 90 °C for 0.5 h to obtain a V(IV) solution. Sulfuric acid was added to adjust the pH of the V(IV) solution to -1. A total of 16.8 g of sodium sulfide (4.2 g each time) was gradually added in 4 times, and the reaction was carried out at 90 °C for 0.5 h to obtain a V(IV) solution for arsenic removal. KOH was added to adjust the pH value of the V(IV) solution for arsenic removal to 5, and VO(OH) was filtered. 2 solid;

[0058] 2) VO(OH) obtained in step 1) 2 The solid was mixed with 80.64 g of sodium peroxide, dissolved in 500 ml of 400 g / L NaOH solution and adjusted to pH 11 with sulfuric acid, reacted at 95 °C for 0.5 h to obtain a pentavalent sodium vanadate solution, then cooled to 2 °C at a rate of 5 °C / min, stirred at a rate of 200 r / min during the cooling process, and the cooled solution was filtered to obtain sodium vanadate crystals; then the sodium vanadate crystals were used to replace VO(OH) 2 The solid was used as a raw material and step 2) was repeated once to obtain 82.5 g of high-purity sodium vanadate crystals with a purity of 99.91% and an As content of 0.06 wt%;

[0059] 3) The high-purity sodium vanadate crystals obtained in step 2) were dissolved in sulfuric acid, and the pH value was adjusted to 5. 60.48 g of oxalic acid was added, and the reaction was carried out at 90 ° C for 0.5 h. Sulfuric acid was added to adjust the pH value of the solution to -1, and 0.24 g of sodium sulfide (0.06 g each time) was added in 4 times, and the reaction was carried out at 90 ° C for 0.5 h to obtain an arsenic-free solution with an arsenic content of 3.2 ppm. NaOH was added to adjust the pH value of the arsenic-free solution to 11, and VO(OH) was obtained by filtration. 2, the VO(OH) 2 After being washed twice with dilute sulfuric acid at pH 6.5 and three times with water, the washed VO(OH) was dissolved in 120 mL of 5 mol / L sulfuric acid. 2 , and a 2.5 mol / L vanadyl sulfate electrolyte was prepared.

[0060] It was determined that the vanadyl sulfate electrolyte prepared in this embodiment contained 58 ppm Na, 0.6 ppm As, 0.8 ppm Al, and 0.6 ppm Si, which met the requirements of GB / T 37204-2018 for first-class quadrivalent vanadium electrolyte.

[0061] Example 6

[0062] A method for preparing vanadium electrolyte by using Bayer process alumina seed liquor crystallized vanadium slag, wherein the main components of the Bayer process alumina seed liquor crystallized vanadium slag include V 5.7%, Na 13.2%, As 2%, P 2.4%, Al 2.2%, and Si 1%, and the method comprises the following steps:

[0063] 1) 400 g of Bayer process alumina seed mother liquor crystallized vanadium slag was dissolved in 100 g / L dilute sulfuric acid at a solid-liquid ratio of 1:1, KOH was used to adjust the pH value of the solution to 4, 52.3 g of potassium oxalate was added, and the reaction was carried out at 80 ° C for 1 h to obtain a V(IV) solution, sulfuric acid was added to adjust the pH of the V(IV) solution to 0, and a total of 88 g of potassium sulfide (17.6 g each time) was gradually added in 5 times, and the reaction was carried out at 80 ° C for 1 h to obtain an arsenic-free V(IV) solution, NaOH was added to adjust the pH value of the arsenic-free V(IV) solution to 10, and VO(OH) was filtered. 2 solid;

[0064] 2) VO(OH) obtained in step 1) 2 The solid was mixed with 69.3 g of potassium peroxide, dissolved in 450 ml of a 500 g / L KOH solution, and the pH value was adjusted to 10 using sulfuric acid. The reaction was carried out at 80 °C for 0.5 h to obtain a pentavalent potassium vanadate solution. The potassium vanadate solution was then cooled to 5 °C at a rate of 4 °C / min. During the cooling process, the solution was stirred at a rate of 20 r / min. The cooled solution was filtered to obtain potassium vanadate crystals. The potassium vanadate crystals were then used to replace VO(OH) 2 The solid was used as a raw material and step 2) was repeated twice to obtain 78 g of high-purity potassium vanadate crystals with a purity of 99.93% and an As content of 0.05 wt%;

[0065] 3) The high-purity potassium vanadate crystals obtained in step 2) were dissolved in sulfuric acid, and the pH value was adjusted to 1, 30.24 g of oxalic acid was added, and the reaction was carried out at 70 ° C for 1 h, sulfuric acid was added to adjust the pH value of the solution to 0, 0.27 g of ammonium sulfide (0.054 g each time) was added in 5 times, and the reaction was carried out at 80 ° C for 1 h to obtain an arsenic-free solution with an arsenic content of 4 ppm, KOH was added to adjust the pH value of the arsenic-free solution to 5, and VO(OH) was obtained by filtration. 2 , the VO(OH) 2 After being washed twice with dilute sulfuric acid at pH 5 and twice with water, VO(OH) was dissolved in 100 mL of 6 mol / L sulfuric acid. 2 , and a 3.5 mol / L vanadyl sulfate electrolyte was prepared.

[0066] It was determined that the vanadyl sulfate electrolyte prepared in this embodiment contained 40 ppm Na, 0.3 ppm As, 0.9 ppm Al, and 0.5 ppm Si, which met the requirements of GB / T 37204-2018 for first-class quadrivalent vanadium electrolyte.

[0067] Comparative Example 1

[0068] A method for preparing vanadium electrolyte by using Bayer process aluminum oxide seed liquor crystallized vanadium slag, wherein the main components of the Bayer process aluminum oxide seed liquor crystallized vanadium slag include V 7.7%, Na 18.4%, As 1.4%, P1.3%, Al 0.6%, and Si 0.3%, and the method comprises the following steps:

[0069] 1) 200 g of Bayer process alumina seed liquor crystallized vanadium slag was dissolved in 80 g / L dilute sulfuric acid at a solid-liquid ratio of 1:3, sulfuric acid was used to adjust the pH value of the solution to 1, 27 g of oxalic acid was added, and the reaction was carried out at 60°C for 2 h to obtain a V(IV) solution, sulfuric acid was added to adjust the pH value of the V(IV) solution to 2, and a total of 4.32 g of sodium sulfide (1.44 g+1.44 g+1.44 g, 1 times the theoretical reaction amount) was gradually added in 3 times, and the reaction was carried out at 60°C for 1 h to obtain an arsenic-free V(IV) solution, NaOH was added to adjust the pH value of the arsenic-free V(IV) solution to 7, and VO(OH) was obtained by filtration. 2 solid;

[0070] 2) VO(OH) obtained in step 1) 2The solid was mixed with 10.2 g of hydrogen peroxide, dissolved in 300 ml of 100 g / L NaOH solution and adjusted to pH 9 using dilute sulfuric acid, reacted at 60 °C for 1 h to obtain a pentavalent sodium vanadate solution, then cooled to 20 °C at a rate of 1.4 °C / min, stirred at a rate of 200 r / min during the cooling process, and the cooled solution was filtered to obtain sodium vanadate crystals; then the sodium vanadate crystals were used to replace VO(OH) 2 The solid was used as a raw material and step 2) was repeated twice to obtain 55.2 g of high-purity sodium vanadate crystals with a purity of 99.43% and an As content of 0.55 wt%;

[0071] 3) The high-purity sodium vanadate crystals obtained in step 2) were dissolved in sulfuric acid, and the pH value was adjusted to 1, 30.24 g of sodium sulfite was added, and the reaction was carried out at 60° C. for 2 h, and NaOH was added to adjust the pH value of the solution to 2, and 0.3 g of sodium sulfide (0.1 g each time) was added in 3 times, and the reaction was carried out at 60° C. for 1 h to obtain an arsenic-free solution with an arsenic content of 17 ppm, and NaOH was added to adjust the pH value of the arsenic-free solution to 7, and VO(OH) was obtained by filtration. 2 , the VO(OH) 2 After being washed twice with dilute sulfuric acid at pH 6.5 and twice with water, 150 mL of 4.2 mol / L sulfuric acid was used to dissolve the washed VO(OH) 2 , and a 1.6 mol / L vanadyl sulfate electrolyte was prepared.

[0072] It was determined that the Na 57 ppm, As 5.6 ppm, Al 1.2 ppm, and Si 1.3 ppm in the vanadyl sulfate electrolyte prepared in this comparative example did not meet the requirements of GB / T 37204-2018 for first-class 4-valent vanadium electrolyte. Compared with Example 1, the amount of arsenic removal precipitant added in this comparative example was too low, and the As in the V(IV) solution could not be removed. 3+ Deep removal results in too high arsenic ion content in the arsenic removal V(IV) solution. Arsenic ions are mixed in high-purity vanadates, reducing their purity. In subsequent processes, arsenic ions are mixed in VO(OH) 2 The vanadium electrolyte is entered into the vanadium electrolyte, causing the arsenic content of the vanadium electrolyte to exceed the standard.

[0073] Comparative Example 2

[0074] A method for preparing vanadium electrolyte by using Bayer process alumina seed liquor crystallized vanadium slag, wherein the main components of the Bayer process alumina seed liquor crystallized vanadium slag include V 8.2%, Na 17.3%, As 1.2%, P 1.5%, Al 1%, and Si 0.4%, and the method comprises the following steps:

[0075] 1) 200 g of Bayer process alumina seed liquor crystallized vanadium slag was dissolved in 70 g / L dilute sulfuric acid at a liquid-solid ratio of 1:5, KOH was used to adjust the pH value of the solution to 3, 5.14 g of elemental sulfur was added, and the reaction was carried out at 40°C for 5 h to obtain a V(IV) solution, sulfuric acid was added to adjust the pH value of the V(IV) solution to 0, 21.12 g of potassium sulfide was added at one time, and the reaction was carried out at 40°C for 1 h to obtain an arsenic-free V(IV) solution, NaOH was added to adjust the pH value of the arsenic-free V(IV) solution to 9, and VO(OH) was obtained by filtration. 2 solid;

[0076] 2) VO(OH) obtained in step 1) 2 The solid was mixed with 52.8 g potassium peroxide, dissolved in 300 ml 150 g / L KOH solution and adjusted to pH 12 using KOH, reacted at 80 °C for 1 h to obtain a pentavalent potassium vanadate solution, then cooled to 10 °C at a rate of 2.5 °C / min, stirred at a rate of 100 r / min during the cooling process, and the cooled solution was filtered to obtain potassium vanadate crystals; then the potassium vanadate crystals replaced VO(OH) 2 The solid was used as a raw material and step 2) was repeated twice to obtain 59.4 g of high-purity potassium vanadate crystals with a purity of 99.34% and an As content of 0.64 wt%;

[0077] 3) The high-purity potassium vanadate crystals obtained in step 2) were dissolved in sulfuric acid, and the pH value was adjusted to 3. 17.28 g of oxalic acid was added, and the reaction was carried out at 40° C. for 5 h. Sulfuric acid was added to adjust the pH value of the solution to 0. 0.418 g of potassium sulfide (0.1054 g each time) was added in 4 portions, and the reaction was carried out at 40° C. for 1 h to obtain an arsenic-free solution with an arsenic content of 20.6 ppm. NaOH was added to adjust the pH value of the arsenic-free solution to 10, and VO(OH) was obtained by filtration. 2 , the VO(OH) 2 After being washed twice with dilute sulfuric acid at pH 6.5 and twice with water, 120 mL of 5 mol / L sulfuric acid was used to dissolve the washed VO(OH) 2 , and a 2 mol / L vanadyl sulfate electrolyte was prepared.

[0078] It was determined that the Na 42 ppm, As 6 ppm, Al 2 ppm, and Si 1.3 ppm in the vanadyl sulfate electrolyte prepared in this comparative example did not meet the requirements of GB / T 37204-2018 for first-class vanadium electrolyte. Compared with Example 2, the arsenic removal precipitant in this comparative example was added once, resulting in S in the V(IV) solution. 2- The concentration increases instantly, S 2- With H in solution +Rapid generation of H 2 S gas reduces the S 2- The amount of As in V(IV) solution 3+ Failure to deeply remove arsenic will reduce the purity of high-purity vanadate and cause the arsenic content in the vanadium electrolyte to exceed the standard.

[0079] Comparative Example 3

[0080] A method for preparing vanadium electrolyte by using Bayer process alumina seed liquor crystallized vanadium slag, wherein the main components of the Bayer process alumina seed liquor crystallized vanadium slag include V 6.8%, Na 15.4%, As 1.9%, P 2%, Al 2%, and Si 1%, and the method comprises the following steps:

[0081] 1) 200 g of Bayer process alumina seed mother liquor crystallized vanadium slag was dissolved in 80 g / L dilute sulfuric acid at a liquid-solid ratio of 1:7, sulfuric acid was used to adjust the pH value of the solution to 0, 20.16 g of sodium sulfite was added, and the reaction was carried out at 25°C for 5 hours to obtain a V(IV) solution, sulfuric acid was added to adjust the pH value of the V(IV) solution to 0, a total of 52.65 g of sodium sulfide (10.53 g each time) was gradually added in 5 times, and the reaction was carried out at 25°C for 2 hours to obtain an arsenic-free V(IV) solution, NaOH was added to adjust the pH value of the arsenic-free V(IV) solution to 11, and VO(OH) was obtained by filtration. 2 solid;

[0082] 2) VO(OH) obtained in step 1) 2 The solid was mixed with 52.65 g of sodium peroxide, dissolved in 250 ml of 200 g / L NaOH solution and adjusted to pH 7 with sulfuric acid, reacted at 40 °C for 1 h to obtain a pentavalent sodium vanadate solution, then cooled to 2 °C at a rate of 0.5 °C / min, stirred at a rate of 250 r / min during the cooling process, and the cooled solution was filtered to obtain sodium vanadate crystals; then the sodium vanadate crystals were used to replace VO(OH) 2 The solid was used as a raw material and step 2) was repeated twice to obtain 40 g of high-purity sodium vanadate crystals with a purity of 99.68% and an As content of 0.12 wt%;

[0083] 3) The high-purity sodium vanadate crystals obtained in step 2) were dissolved in sulfuric acid, and the pH value was adjusted to 0. 9.72 g of formic acid was added, and the reaction was carried out at 25° C. for 5 h. Sulfuric acid was added to adjust the pH value of the solution to 0. 0.22 g of sodium sulfide (0.044 g each time) was added in 5 portions, and the reaction was carried out at 25° C. for 2 h to obtain an arsenic-free solution with an arsenic content of 19.3 ppm. NaOH was added to adjust the pH value of the arsenic-free solution to 14, and VO(OH) was obtained by filtration. 2 , the VO(OH)2 After being washed twice with dilute sulfuric acid at pH 6.5 and twice with water, 120 mL of 5 mol / L sulfuric acid was used to dissolve the washed VO(OH) 2 , and a 1.7 mol / L vanadyl sulfate electrolyte was prepared.

[0084] It was determined that the contents of Na 23 ppm, As 2.5 ppm, Al 15 ppm, and Si 10 ppm in the vanadium sulfate electrolyte prepared in this comparative example did not meet the requirements of GB / T 37204-2018 for first-class 4-valent vanadium electrolyte. Compared with Example 3, the stirring rate of the crystallization process in this comparative example was too high, the crystal size was too small, the residual liquid inclusion was large, and the impurity elements such as As, Al, and Si in the solution were not deeply removed, resulting in the content of impurity elements such as As, Al, and Si in the vanadium electrolyte finally prepared exceeding the standard.

[0085] Comparative Example 4

[0086] A method for preparing vanadium electrolyte by using Bayer process alumina seed liquor crystallized vanadium slag, wherein the main components of the Bayer process alumina seed liquor crystallized vanadium slag include V 10.5%, Na 15.5%, As 1%, P 2.4%, Al 1.2%, and Si 0.4%, and the method comprises the following steps:

[0087] 1) 500 g of Bayer process alumina seed liquor crystallized vanadium slag was dissolved in 40 g / L dilute sulfuric acid at a solid-liquid ratio of 1:9, sulfuric acid was used to adjust the pH value of the solution to 0, 97.6 g of potassium sulfite was added, and the reaction was carried out at 30 ° C for 5 h to obtain a V(IV) solution, sulfuric acid was added to adjust the pH of the V(IV) solution to -1, a total of 20.4 g of ammonium sulfide (5.1 g each time) was gradually added in 4 times, and the reaction was carried out at 30 ° C for 2 h to obtain an arsenic-free V(IV) solution, NaOH was added to adjust the pH value of the arsenic-free V(IV) solution to 13, and VO(OH) was obtained by filtration. 2 solid;

[0088] 2) VO(OH) obtained in step 1) 2 The solid was mixed with 70 g of hydrogen peroxide, dissolved in 1 L of 330 g / l KOH solution and adjusted to pH 8 with sulfuric acid, reacted at 30 °C for 2 h to obtain a pentavalent potassium vanadate solution, then cooled to 2 °C at a rate of 0.1 °C / min, stirred at a rate of 200 r / min during the cooling process, and the cooled solution was filtered to obtain 225 g of potassium vanadate crystals with a purity of 99.6% and an As content of 0.2 wt%;

[0089] 3) The high-purity potassium vanadate crystals obtained in step 2) were dissolved in sulfuric acid, and the pH value was adjusted to -1, 61.8 g of potassium oxalate was added, and the reaction was carried out at 30 ° C for 5 h, sulfuric acid was added to adjust the pH value of the solution to -1, 0.75 g of ammonium sulfide was added three times (0.25 g each time), and the reaction was carried out at 30 ° C for 2 h to obtain an arsenic-free solution with an arsenic content of 9.1 ppm, KOH was added to adjust the pH value of the arsenic-free solution to 13, and VO(OH) was obtained by filtration. 2 , the VO(OH) 2 After being washed once with dilute sulfuric acid at pH 6.5 and three times with water, the washed VO(OH) was dissolved in 270 mL of 6 mol / L sulfuric acid. 2 , and a 3.5 mol / L vanadyl sulfate electrolyte was prepared.

[0090] It was determined that the content of Na 56 ppm, As 1.4 ppm, Al 63 ppm, and Si 23 ppm in the vanadium sulfate electrolyte prepared in this comparative example did not meet the requirements of GB / T 37204-2018 for the first-class 4-valent vanadium electrolyte. Compared with Example 4, the number of crystallizations in this comparative example was too small, and the impurity elements such as As, Al, and Si in the solution were not deeply removed, resulting in the content of impurity elements such as As, Al, and Si in the vanadium electrolyte finally prepared exceeding the standard.

[0091] Comparative Example 5

[0092] A method for preparing vanadium electrolyte by using Bayer process alumina seed liquor crystallized vanadium slag, wherein the main components of the Bayer process alumina seed liquor crystallized vanadium slag include V 9.6%, Na 13.2%, As 1.2%, P 2%, Al 1.3%, and Si 0.5%, and the method comprises the following steps:

[0093] 1) 300 g of Bayer process alumina seed liquor crystallized vanadium slag was dissolved in 40 g / L dilute sulfuric acid at a solid-liquid ratio of 1:10, and the pH value of the solution was adjusted to 5 with NaOH, and 82.3 g of sodium oxalate was reacted at 90 °C for 0.5 h to obtain V(IV) solution;

[0094] 2) VO(OH) obtained in step 1) 2 The solid was mixed with 80.64 g of sodium peroxide, dissolved in 500 ml of 400 g / L NaOH solution and adjusted to pH 11 with sulfuric acid, reacted at 95 °C for 0.5 h to obtain a pentavalent sodium vanadate solution, then cooled to 2 °C at a rate of 5 °C / min, stirred at a rate of 200 r / min during the cooling process, and the cooled solution was filtered to obtain sodium vanadate crystals; then the sodium vanadate crystals were used to replace VO(OH) 2The solid was used as a raw material and step 2) was repeated once to obtain 82.5 g of high-purity sodium vanadate crystals with a purity of 99.4% and an As content of 0.58 wt%;

[0095] 3) The high-purity sodium vanadate crystals obtained in step 2) were dissolved in sulfuric acid, and the pH value was adjusted to 5. 60.48 g of oxalic acid was added, and the reaction was carried out at 90 ° C for 0.5 h. Sulfuric acid was added to adjust the pH value of the solution to -1. 0.24 g of sodium sulfide (0.06 g each time) was added in 4 times, and the reaction was carried out at 90 ° C for 0.5 h to obtain an arsenic-free solution with an arsenic content of 29.5 ppm. NaOH was added to adjust the pH value of the arsenic-free solution to 11, and VO(OH) was obtained by filtration. 2 , the VO(OH) 2 After being washed twice with dilute sulfuric acid at pH 6.5 and three times with water, the washed VO(OH) was dissolved in 120 mL of 5 mol / L sulfuric acid. 2 , and a 2.5 mol / L vanadyl sulfate electrolyte was prepared.

[0096] It was determined that the vanadium sulfate electrolyte prepared in this comparative example contained 22 ppm Na, 5 ppm As, 0.4 ppm Al, and 0.4 ppm Si, which did not meet the requirements of GB / T 37204-2018 for first-class 4-valent vanadium electrolyte. Compared with Example 5, this comparative example lacked the first precipitation arsenic removal process, and most of the arsenic in the raw material entered the vanadate solution. Crystallization and the second precipitation arsenic removal could not completely remove the excess arsenic, resulting in an excessive arsenic concentration in the final vanadium electrolyte.

[0097] Comparative Example 6

[0098] A method for preparing vanadium electrolyte by using Bayer process alumina seed liquor crystallized vanadium slag, wherein the main components of the Bayer process alumina seed liquor crystallized vanadium slag include V 5.7%, Na 13.2%, As 2%, P 2.4%, Al 2.2%, and Si 1%, and the method comprises the following steps:

[0099] 1) 400 g of Bayer process alumina seed mother liquor crystallized vanadium slag was dissolved in 100 g / L dilute sulfuric acid at a solid-liquid ratio of 1:1, KOH was used to adjust the pH value of the solution to 4, 52.3 g of potassium oxalate was added, and the reaction was carried out at 80 ° C for 1 h to obtain a V(IV) solution, sulfuric acid was added to adjust the pH of the V(IV) solution to 0, and a total of 88 g of potassium sulfide (17.6 g each time) was gradually added in 5 times, and the reaction was carried out at 80 ° C for 1 h to obtain an arsenic-free V(IV) solution, NaOH was added to adjust the pH value of the arsenic-free V(IV) solution to 10, and VO(OH) was filtered. 2 solid;

[0100] 2) VO(OH) obtained in step 1) 2 The solid was mixed with 69.3 g of potassium peroxide, dissolved in 450 ml of a 500 g / L KOH solution, and the pH value was adjusted to 10 using sulfuric acid. The reaction was carried out at 80 °C for 0.5 h to obtain a pentavalent potassium vanadate solution. The potassium vanadate solution was then cooled to 5 °C at a rate of 4 °C / min. During the cooling process, the solution was stirred at a rate of 20 r / min. The cooled solution was filtered to obtain potassium vanadate crystals. The potassium vanadate crystals were then used to replace VO(OH) 2 The solid was used as a raw material and step 2) was repeated twice to obtain 78 g of high-purity potassium vanadate crystals with a purity of 99.93% and an As content of 0.05 wt%;

[0101] 3) The high-purity potassium vanadate crystals obtained in step 2) were dissolved in sulfuric acid, and the pH value was adjusted to 1. 30.24 g of oxalic acid was added, and the reaction was carried out at 70 °C for 1 h to obtain a V(IV) solution with an arsenic content of 30 ppm. KOH was added to adjust the pH value of the V(IV) solution to 5, and VO(OH) was obtained by filtration. 2 , the VO(OH) 2 After being washed twice with dilute sulfuric acid at pH 5 and twice with water, VO(OH) was dissolved in 100 mL of 6 mol / L sulfuric acid. 2 , and a 3.5 mol / L vanadyl sulfate electrolyte was prepared.

[0102] It was determined that the Na 0 ppm, As 10 ppm, Al 0.9 ppm, and Si 0.5 ppm in the vanadyl sulfate electrolyte prepared in this comparative example did not meet the requirements of GB / T 37204-2018 for first-class vanadium electrolyte. Compared with Example 6, this comparative example lacks the second precipitation and arsenic removal process, and the arsenic remaining in the V(IV) solution is mixed in VO(OH) 2 This results in the arsenic concentration in the final vanadium electrolyte exceeding the standard.

[0103] It should be noted that, according to the above embodiments of the present invention, those skilled in the art can fully realize the full scope of the independent claims and dependent rights of the present invention, and the implementation process and method are the same as the above embodiments; and the part not described in detail in the present invention belongs to the well-known technology in the field. However, the protection scope of the present invention is not limited to this, and any changes or substitutions that can be easily thought of by any person familiar with the field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A method for preparing vanadium electrolyte by using alumina seed solution to crystallize vanadium slag, characterized in that: The method comprises the following steps: 1) Dissolve the crystallized vanadium slag of the Bayer process alumina seed liquor in acid, adjust the solution pH to 0-5, add a first reducing agent according to 1.1-3 times the theoretical amount of the first reducing agent required for reducing V(V) and As(V) to V(IV) and As(III), react at 25-99° C. for 0.5-5 hours to obtain a V(IV) solution, adjust the pH of the V(IV) solution to -1-5, add an arsenic removal precipitant in multiple times according to 3-9 times the theoretical amount of the arsenic removal precipitant required for removing As(III), and react at 25-99° C. for 0.5-2 hours to obtain an arsenic-removed V(IV) solution, adjust the pH of the arsenic-removed V(IV) solution to 5-14, and filter to obtain VO(OH)2 solid; wherein the first reducing agent includes one or more of sodium sulfide, elemental sulfur, sulfur dioxide, sulfite, oxalic acid, oxalate, glucose, fructose, sucrose, and formic acid; 2) placing the VO(OH)2 solid obtained in step 1) in an alkaline solution and adjusting the pH value to 7-14, adding an oxidant in an amount of 1.5-5 times the theoretical amount required for oxidation of V(IV) to V(V), reacting at 25-99°C for 0.5-2 h to obtain a pentavalent vanadate solution, then cooling the vanadate solution to 0-25°C at a rate of 0.1-5°C / min, and stirring the solution at a rate of 20-200 r / min, filtering the cooled solution to obtain vanadate crystals; then repeating step 2) more than once using the vanadate crystals instead of the VO(OH)2 solid as a raw material to obtain high-purity vanadate crystals with a purity greater than 99.9%; 3) dissolving the high-purity vanadate crystals obtained in step 2) in acid, and adjusting the pH value to 0-5, adding a second reducing agent according to 1.1-3 times the theoretical amount of the second reducing agent required for reducing V(V) and As(V) to V(IV) and As(III), reacting at 25-99° C. for 0.5-5 h, adjusting the pH value of the solution to -1-5, adding an arsenic removal precipitant in multiple times according to 3-9 times the theoretical amount of the arsenic removal precipitant required for removing As(III), and reacting at 25-99° C. for 0.5-2 h to obtain an arsenic removal solution, adjusting the pH value of the arsenic removal solution to 5-14, filtering to obtain VO(OH)2, washing the VO(OH)2 with acid and water, and dissolving the washed VO(OH)2 with acid to prepare a vanadium electrolyte; wherein the second reducing agent comprises one or more of sodium sulfide, elemental sulfur, sulfur dioxide, sulfite, oxalic acid, oxalate, glucose, fructose, sucrose, and formic acid.

2. The method according to claim 1, characterized in that The Bayer process alumina seed liquor crystallized vanadium slag includes V2O5 10-20 wt%, Al 0.5-1 wt%, As 0.5-3 wt%, P 1-3 wt%, and Si 0.1-1 wt%.

3. The method according to claim 1, characterized in that In step 1), the acid comprises dilute sulfuric acid with a concentration of 40-100 g / L, and the solid-liquid ratio of the Bayer process alumina seed liquor crystallized vanadium slag to the dilute sulfuric acid is 1:1-1:10 g / mL.

4. The method according to any one of claims 1 to 3, characterized in that: The pH value is adjusted specifically by adding one or more acids including sulfuric acid and hydrochloric acid to the solution for adjustment when the pH value needs to be lowered, and adding one or more bases including NaOH and KOH to the solution for adjustment when the pH value needs to be increased.

5. The method according to any one of claims 1 to 3, characterized in that: The arsenic removal precipitant includes one or more of sodium sulfide, potassium sulfide, ammonium sulfide, hydrogen sulfide, and thiourea.

6. The method according to any one of claims 1 to 3, characterized in that: The multiple times in step 1) is 3 to 5 times.

7. The method according to any one of claims 1 to 3, characterized in that: In the step 2), the oxidant includes one or more of hydrogen peroxide, sodium peroxide, potassium peroxide, ammonium persulfate, sodium persulfate, and potassium persulfate.

8. The method according to any one of claims 1 to 3, characterized in that: In the step 2), the alkali solution includes one or more of NaOH and KOH solutions with a concentration of 50-500 g / L.

9. The method according to any one of claims 1 to 3, characterized in that: The multiple times in step 3) is 3 to 5 times.

10. The method according to any one of claims 1 to 3, characterized in that: In step 3), the reagent used for the acid washing is dilute sulfuric acid with a pH of 5 to 7, the number of washing times for the acid washing is 1 to 3 times, and the number of washing times for the water washing is 2 to 3 times; the reagent used for the acid dissolution is sulfuric acid with a concentration of 4 to 6 mol / L.

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